1. Field
The exemplary embodiments generally relate to synthetic jets and, more particularly, to canceling sound emanating from synthetic jet generators.
2. Brief Description of Related Developments
A synthetic jet generator typically includes a volume with one or more apertures. The volume is generally pumped at a single frequency in the audible range. to force air in and out of the one or more apertures to form a synthetic jet. While producing an effective synthetic jet, the reciprocating, single frequency action of the pumping mechanism of the synthetic jet generator generally produces high sound levels at the drive frequency. High sound levels may also be produced by the resulting synthetic jet, however, in practical applications, the synthetic jet produces noise outside of a supporting structure, while the pumping mechanism produces noise inside the structure.
Traditional methods of increasing sound attenuation typically include passive treatments, for example, adding mass or dampening materials. However, adding mass may generally decrease performance, in particular for in flight applications. Furthermore, because acoustic propagation paths are difficult to analyze, passive treatments are generally applied conservatively, resulting in adding more mass than required.
It would be advantageous to provide a device for cancelling noise caused by the pumping action of a synthetic jet generator without adding excessive treatments.